Application of molecular biology to individualize therapy for patients with liposarcoma
Liposarcomas are one the most common of over 50 histologic subtypes of soft tissue sarcomas that are mostly resistant to chemotherapy. Histologically, liposarcomas themselves are heterogeneous and fall into four distinct subtypes: well-differentiated/atypical lipomatous tumor, dedifferentiated liposarcoma, myxoid (round cell) liposarcoma, and pleomorphic liposarcoma. Surgical resection with negative margins remains the mainstay for definitive treatment for operable disease. For unresectable disease, retrospective studies have identified myxoid (round cell) and pleomorphic sarcomas to be relatively responsive to chemotherapy. Recent studies have identified distinct genetic aberrations that not only aid in the diagnosis of particular liposarcoma subtypes, but represent actionable targets as they are considered central to disease pathogenesis. Cyclin-dependent kinase 4 (CDK4) and murine double minute 2 (MDM2) are overexpressed in well-differentiated and dedifferentiated liposarcomas and offer tantalizing opportunities that are being pursued in clinical trials. Myxoid (round cell) liposarcomas appear to be sensitive to trabectedin, which is currently under U.S. Food and Drug Administration (FDA) review. Liposarcomas do not represent a uniform disease and understanding the underlying molecular mechanism will help not only in accurate diagnosis but in selecting the appropriate treatment.